With the development of entertainment and media industry, consumers become more sensitive to the quality of sound quality. In various venues such as, theater, concert and home theater and other application occasion of audio player equipment, requirement for audio adjust function of audio processing system is getting higher and higher.
In the technosphere of audio mixer technology, equalizers and compressors have been widely used in the process of audio signal. With the combined application of an equalizer and compressor, modulation distortion of D-class power amplifier can be controlled during the maximum power output, and maximum output can also be adjusted. In the application of digital signal processing (DSP), the compressor is series connected to the equalizer, the input signal is input to the equalizer for processing then delivered to compressor for compressing and limiting, and received by the signal output device. Generally, only one threshold is setup in the compressor during the application above, and the threshold is a constant value for full-brand audio signal. However, as the voltage output corresponding to each frequency is different, it leads to the result that the trigger threshold for volume is different. Bandwidth of triggered compressor becomes larger and larger with the volume of each frequency is increasing. When the volumes of each frequency are larger than the threshold, the shape of the output signal becomes flat, and cannot reach the effect of audio adjustment.